Hard disk drive (HDD) based storage technologies are currently finding use in an increasingly diverse range of technological applications. This includes conventional consumer electronic devices such as digital music players, digital cameras, movie devices and advanced technology cell phones. Moreover, HDD based products are also being introduced into the automotive realm, where both in car and under the hood applications are being considered. In car applications include the provision of support for entertainment, navigation and communications systems. Under the hood uses include data storage systems for storing engine operating history.
One of the challenges that HDD systems encounter is a requirement that their environmental operation range far exceed that found in the office-like environment that most information technology (IT) based HDDs are operated in. For example, typical prior art HDDs have a specified operating temperature range of 5 C to 60 C with relatively benign rates of change. However, auto manufacturers would like to use HDD's capable of operating to at least −40 to 80 C with the capacity to manage very aggressive rates of temperature change. Under hood use may demand even more extreme requirements.
Conventional HDD's are challenged to meet these requirements in several critical areas. Component lubrication is one such area. Lubricants are used in several places throughout the HDD structure including the spindle motor system, actuator pivot system and head-to-disk interface. Unfortunately, the lubricants currently in widespread use are not capable of acceptable operation at extreme temperatures. More specifically, lubricant viscosity increases at very low temperatures while evaporation/degradation is encountered at high temperatures.
Moreover, water vapor condensation that can form inside conventional HDD's is also a significant problem. It should be appreciated that water droplets that can result from such condensation and that can occur at the head-to-disk interface can be fatal to the device.
Modern HDD's typically utilize a fluid bearing based spindle motor system to rotate the disks. It should be noted that this very sensitive technology can be adversely affected by temperature extremes in several ways. Specifically, clearance changes due to thermal expansion and contraction can render bearings useless at temperature extremes because the mechanical clearances in the bearing system are only several microns wide to begin with. Moreover, thermally induced tilts that can result from the expansion and contraction of motor materials can cause track mis-registration to a degree that is greater than the HDD can tolerate. In addition, HDD motors are limited by the lubrication issues discussed above.
Changes have been proposed to make conventional HDD systems capable of managing automobile like temperature conditions. It should be noted that the existing proposals are expensive and difficult to implement. More specifically, the development of new lubricant systems is both expensive and difficult to implement. Hermetically sealed HDDs have been proposed that would partially ruggedized the devices, but as with the other proposals this solution requires significant development and adds cost. The electronics modules for a HDD can be ruggedized to achieve the required temperature demands but significant cost is added.